1. Field of the Invention
The present invention relates to an organic electroluminescence element including a host material containing an alkyl group as a substituent with a specified structure.
2. Description of the Related Art
In recent, organic electroluminescence elements have been significantly improved and widely applied to displays and illuminations because of the possibilities of low power consumption, high luminance, enlargement of a color reproduction range due to diversification of emission wavelength, rapid response, lighter weight, and thinner size.
It is known that luminance of an organic electroluminescence element decreases with time due to the low purity of an organic compound.
Japanese Patent Laid-Open No. 2002-175885 discloses an organic electroluminescence element including at least one organic compound layer formed using an organic compound material which contains impurities composed of a halogen-containing compound at a concentration of less than 1000 ppm. Further, an organic electroluminescence element formed using an organic compound material containing less than 500 ppm of impurities is disclosed.
However, these techniques cannot sufficiently secure durability in driving for a long time.